The correct answer is - B. the hydrosphere.
Our planet has four spheres, the lithosphere, the atmosphere, the hydrosphere, and the biosphere.
The lithosphere is represented with the rigid outer part of the Earth, the crust and the upper part of the mantle.
The atmosphere is represented in the gassy layers surrounding the planet.
The hydrosphere is represented with all of the water on the planet, be it on the surface or inside of the ground.
The biosphere is is represented with the living organisms on the planet, or rather in all of the above spheres.